Physical properties measurements at Hole 1083A included measurements with the MST on whole-round sections of cores from each hole. Discrete velocities, index properties, vane-shear, and thermal conductivity measurements were conducted on half-split cores (see "Explanatory Notes" chapter, this volume).
Index properties (gravimetric wet bulk density, porosity, and moisture content) were generally determined on one or two samples (volume = ~10 cm3) per working-half section on all cores from Hole 1083A. Method C was used at this site (see "Explanatory Notes" chapter, this volume).
Compressional (P-wave) velocity and undrained vane shear strength measurements were made at a resolution of one or two sampling points per section. For discrete P-wave velocity measurements, the modified Hamilton Frame was used. Thermal conductivity was obtained on every second section in every core from Hole 1083A by inserting a probe into the unsplit core (see "Explanatory Notes" chapter, this volume).
GRAPE density (Fig. 23), P-wave velocity (Fig. 24), and magnetic susceptibility (Fig. 25A) were determined every 2 cm for the first 10 cores (0–85 mbsf). MST data are included on CD-ROM (back pocket, this volume). Below 85 mbsf, the resolution was reduced to 4 cm. Compressional velocities were recorded at an amplitude threshold of 100 incremental units to exclude weaker signals. The MST P-wave logger did not record any signals below 125 mbsf (Fig. 24). In general, MST velocities and discrete velocities seem to correlate in some intervals between 0 and 125 mbsf. MST P-wave values appear to be lower than discrete velocity values over the entire depth range.
Magnetic susceptibility (Fig. 25A) and GRAPE density (Fig. 23) show a high correlation over the entire depth range of 200 m. Index properties wet bulk density values follow the GRAPE density profile over the entire depth range. Because only minor cracks and voids in the sediments were observed at Hole 1083A, both data sets correspond to each other very well. GRAPE density and wet bulk density values display a higher overall variation between 0 and 70 mbsf than below 70 mbsf.
All physical properties data sets reveal clear and pronounced cyclicities, which will be subject to further detailed analyses on shore. However, thorough editing will be required to correct for different types of deformation within cores and between holes.
Discrete velocities range between 1520 and 1590 m/s between 0 and 200 mbsf. The P-wave logger of the MST recorded lower values from 0 to 125 mbsf (Fig. 24). At depths of 4, 32, and 83 mbsf, high-velocity peaks are noticed. Wet bulk and GRAPE density profiles show a sharp positive density gradient only at ~115 mbsf (Fig. 23). Density and velocity profiles correspond to each other between 5 and 50 mbsf and for most of the depth interval between 135 and 200 mbsf, but show a negative correlation in other depth intervals.
Results of discrete measurements of wet bulk density, porosity, and moisture content are illustrated in Fig. 26A, Fig. 26B, and Fig. 26C, respectively (also see Table 14 on CD-ROM, back pocket, this volume). The density values vary between 1250 and 1800 kg/m3. The overall trend of the wet bulk density profile shows increasing values in the upper 50 m and significant variability below this depth. Below 50 mbsf, a decrease in wet bulk density can be noticed, with a minimum at 65 mbsf (corresponding to a local velocity maximum). At 115 mbsf, the highest density value for Hole 1083A is found (1680 kg/m3). Density decreases slightly below a depth of 115 mbsf, but variations confirm that small-scale cycles are present, as observed in GRAPE density and magnetic susceptibility core logs.
In general, porosity and moisture profiles show the expected inverse correlation with the wet bulk density curve. Porosities decrease from 82% in the top section to lowest values of 65% (Fig. 26B). Moisture content varies between 65% at the top of Hole 1083A and 42% (Fig. 26C).
The thermal conductivity profile (Fig. 25B) at Hole 1083A was measured in every second core section (see "Explanatory Notes" chapter, this volume). The profile is similar to wet bulk and GRAPE density profiles over most of the depth range at Hole 1083A (Fig. 23).
Undrained vane-shear measurements were performed in the bottom part of each core section. The profile between 0 and 200 mbsf shows little variation in vane shear strength from the top of Hole 1083A to 200 mbsf, except between 55 and 65 mbsf. The shear strength increases slightly over the entire depth range at Hole 1083A. As observed at previous sites, local maxima in shear strength are usually observed in the middle of each core at Site 1083. Lower values coincide mostly with the top and the bottom of each core where gas expansion may have changed the sediment structure significantly.